Although still broadly available across the world, the traditional, well established, circuit switch (CS) mobile voice service with its well-known ability to provide subscribers high Quality of Experience (QoE) since the introduction of 2G services, is clearly fading.
The evolution to 3.5G (HSPA+) already unleashed the technical means for Voice over Internet Protocol (VoIP) based solutions using mobility, such as the more or less free over-the-top (OTT) voice services like Skype and Viber.
Lately, by the means of more widely spread and more mature LTE networks, VoIP solutions have become higher quality, and, more importantly, have allowed leading LTE carriers to deploy Voice over LTE (VoLTE) as the voice service solution with guaranteed QoE.
A User’s Perspective on Voice over WiFi Calling